PORTLAND — Average temperatures in various parts of the Pacific Northwest have risen 1.3 to 2.5 degrees since the mid-20th century, forcing changes in how vineyards and wineries operate, speakers at the annual Oregon Wine Symposium said.

Climate change has altered the timing of harvest, changed grape ripening profiles and forced growers and wine makers to account for fluctuating sugar and acid balances and to deal with new pests and diseases, said Greg Jones, a Southern Oregon University professor who specializes in wine climatology.

The past year was the warmest in recorded history globally, Jones said. The “heat content” of the world’s oceans has increased tremendously, he said, which likely will have dramatic impact on weather patterns. “This may be the real issue as we go forward,” Jones said.

Jones and his counterpart from France’s famed Burgundy region, Benjamin Bois, headed a discussion that attracted an estimated 200 people. Mark Chien, coordinator of Oregon State University’s Wine Research Institute, moderated the discussion. Chien noted that Oregon’s niche success within the wine industry began with cool weather grapes, Pinot noir. A warming challenges the industry, he said. The wine symposium and accompanying trade show attract about 1,400 people annually to the Oregon Convention Center in Portland. The agenda each year includes detailed discussions of grape growing and wine making. Many of the sessions included Spanish interpretation, a nod to the workforce in most vineyards.

The trade show annually features equipment dealers, label makers and suppliers of corks, barrels and tanks, among many others. Vendor booths ranged from one staffed by the Davis Wright Tremaine law firm, which has a wineries, breweries and distilleries practice group, to MaxYield Falconry, which uses falcons to chase pest birds from vineyards, orchards or berry fields.

The climate change presentation was among the better-attended sessions. Bois, a professor of viticulture and climatology at the University de Bourgogne in France, lent some perspective to the relative youth of the West Coast wine industry when he said 2003 was the earliest Burgundy harvest on record — which dates to the 14th century.

But he said the region’s Pinot noir wine from 2003 is in good shape, suggesting there is some “range and space” within a warming environment in which wine quality is not harmed.

“That does not mean there are not some challenges in climate change,” Bois said.

He said temperature increases linked to climate change have shortened the grape growing season in Burgundy by eight days. Researchers compared bud burst to harvest records from 1951-2000 with records kept 2000-2015, he said. The growth process that took 162 days in earlier times now is done in 154 days, he said, and starts five days earlier. That puts grapes somewhat more at risk for spring frost or summer rain, Bois said.

He said some vineyards in southern France now irrigate, after centuries of not doing so. Soil temperature has increased at a greater rate than air temperature, with unknown impact.

“It’s a black box, we really don’t know what’s going on with soil,” he said.